Because Paw costs more than an impulse buy and there is no in-app purchase approach, you have to fish around and find the non-App Store version to try. But it is absolutely worth it. This is the “killer app” for REST API work/exploration. Note the 5 star rating. A rarity as I set a lifetime limit of my age for 5 star ratings.
Paw’s operation is superb and has just about everything you ever wanted in an app that you use for REST interface decoding; from a beginner REST explorer to the experienced ObjC / Cocoa developer needing to cut some trial & error out of the software development cycle. While the price is a little high, high enough to make you look around for an alternative, it is not out of reason. There are free tools out there that can give you pieces of what Paw can do but not all in one place and not all of Paw. And the more you use Paw, the more you find it can do. At a certain point you feel good in supporting these guys because they really knocked it out of the park with Paw. And they read these reviews and take action. (Found a thorn, now it is gone)
Finally explored the code generators for the app and availble via the web page that integrates with Paw. The approach is clean, the code is KISS, does not try to impress you with being fancy, just getterdun style. Use this interface once and the time it saves you pays for Paw.
If you do anything with web services, REST / SOAP, Objective C to HTML, this tool is invaluable. Best developer tool I have bought since CodeWarrior.